A Homemade Bubble Robot for the Kids

Kids generally can be amused pretty easily, but when jangling keys stop holding their interest you might want to take a look at [drenehtsral]’s new project. He’s created an automatic bubble robot (YouTube link) that keeps the kids endlessly entertained!

The project started as an idea at a festival where one of [drenehtsral]’s kids took great interest at a bubble machine. [drenehtsral] had never heard of a bubble machine before, but it turns out that it’s pretty simple in practice. All that’s required is a tank of soapy water, a motor to turn the bubble wands, and a fan to form the bubbles and make them waft gently through the air.

[drenehtsral] also used a 12V battery for power, some other hardware to hold it all together, and a 5V regulator and some other control electronics for the fan and the motor. He notes that he could have bought a bubble machine but in true hacker style found it fun to build himself. The next step in this project could be something to vary the size of the bubbles, or perhaps a set of wheels for the robot so it can entertain the kids on the move!

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10 thoughts on “A Homemade Bubble Robot for the Kids”

See while this might not be a difficult hack or whatever, his kids will see that you don’t have to just buy everything, you can make a lot of it yourself.
This might well be the spark that makes these kids try to figure out how stuff works, and have a go themselves.
So before all the “Not a hack” hate begins;
kudos from Twibz

(ok so just read my comment and it looks like it belongs on reddit or huffpost, so “down with this sort of thing, newfags” etc etc)

You’ve hit the nail on the head [twibz]:
A lot of the point of this (aside from being a good way to have fun with the kids) is to demonstrate that with enough effort, experimentation, and patience you can build all sorts of fun/interesting/cool things.
As for curiosity about how stuff works the older one must have just inherited it because he has eschewed bedtime stories in favor of “machines” from “The New Way Things Work” and always wants to build imaginary devices (along with the occasional real one).

You can get big containers of bubble fluid at Walmart, dollar stores, etc. The ingredients are typically listed on the bottle. Other than a surfactant (soap), the primary ingredient responsible for “going big” is typically propylene glycol (PG). Some personal lubricants are almost entirely PG, making for a readily available (though expensive) source for DIY experiments.

I did a quick Google search to double check I remembered PG’s name correctly, which turned up a forum dedicated to big bubble enthusiasts. :) Here’s the link:

So the recipe I’ve been using is cheap and easy, but has a couple drawbacks:

1 quart hot tap water
2/3 cup Palmolive dish soap (probably any liquid soap would do with the exception of soaps engineered not to make bubbles such as laundry soap).
1/2 cup corn syrup
2 tablespoons corn starch

Stir well while hot, then cool to room temperature, stir before using to try and keep as much of the corn starch as possible in suspension. If you use a bubble machine with rotating wands it should agitate the solution enough as it runs.

Now for the drawbacks: If you don’t use all of your bubble mix and decide to store it, be prepared for an _awful_ stench as the corn syrup and corn starch apparently will ferment despite the soapiness of the water. That being said, so long as it isn’t too far gone it will still make bubbles even if it is a bit fermented.

Evidently you can replace the corn syrup and corn starch with glycerine for a non-fermenting bubble mix that will perform as well or better but I didn’t have any glycerine lying around the pantry to verify this,